The present invention relates to a method for producing a catalytic converter having a monolith wrapped in a mat and a housing, and an apparatus for producing a catalytic converter
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Catalytic converters are used for post-treatment of exhaust gases in vehicles having a combustion engine. The catalytic converters typically include a housing, in which a monolith, for example a ceramic substrate, is arranged. The monolith is wrapped in a mat, which fills a gap between the monolith and the housing, thereby securing the position of the monolith. The housing may be made, for example, from a tube as a single piece made or may be made of several housing parts, which are connected to each other with screws or by welding. The mat is used to secure the position of the monolith inside the housing and to ensure the alignment in this position over various temperatures when operating under different loads. The monolith also protects the mat from damage because the monolith is by far one of the most expensive components of the catalytic converter. The monolith has typically a cylindrical geometry, wherein the diameter of the monolith can vary for production-related reasons. It is easier to adapt the housing to the overall dimensions of the monolith in production by taking into account the average diameter of the monolith.
Several methods are used in the art for enclosing a monolith for a catalytic converter in a housing. One of these methods is described in EP 1 445 443 A1. In this method, a sheet metal piece is cut to a predetermined size commensurate with the dimensions of the monolith and formed into a housing. The edges are connected by soldering. The outside dimensions of the monolith are determined by a contact-less measurement performed in a measuring station, wherein the monolith is scanned with a laser at defined measurement positions and an average diameter of the monolith is determined from the measured diameters. Disadvantageously, optical measurement systems with the required higher accuracy a relatively expensive and susceptive to failure; moreover, the exact positioning of monolith and laser as well as setting the measurement points increases the complexity.
It would therefore be desirable and advantageous to obviate prior art shortcomings and to provide a simplified method for producing a catalytic converter as well as an apparatus for producing the catalytic converter.